Overview

Brief Summary

The genus Oncorhynchus (family Salmonidae) contains the many subspecies of Pacific salmon (seven species) and Pacific trout (four species). Oncorhynchus is placed in the family Salmonidae, along with two other genera: Salmo (mostly trouts of European origin) and Salvelinus (char). Relationships among salmonid species have long been controversial, and the many studies of molecular and fossil data have shown inconsistencies.
The name Oncorhynchus is derived from the Greek onkos ("hook") and rynchos ("nose"), in reference to the hooked jaws (the "kype") that males develop in the mating season. Most Oncorhynchus species are anadromous (migrate between salt and fresh water), some strains migrate enormous distances (traveling up to 2500 miles from home) between Pacific waters and the Bering sea and crossing international boundaries which complicate management issues for these desirable fish. After feeding at sea the fish leave the ocean, often to overcome huge obstacles on their way to return to the same part of their natal stream. They do not feed when they return to streams and all anadromous strains except the Steelhead are semelparous (die after spawning).
The complicated life histories and limited ranges of Oncorhynchus strains make them particularly vulnerable to extinction due to human activities. Wilson and Turner (2009) write, “All species and subspecies in this group are threatened, endangered, sensitive, or species of conservation concern in portions of their native ranges”. Habitat destruction, hydroelectric dams, and overfishing have contributed to the serious decline and extinction of Oncorhynchus species. For many native strains, competition from hatchery fish, including the Atlantic salmon (Salmo salar) recently introduced into Pacific waters, is also a factor of great concern for survival.
(Angler innovations; NOAA ESA status listings; Pacific Salmon Commission; U.S. Fish and Wildlife Service; Wikipedia 2012; Wilson and Turner 2009)

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Oncorhynchus

Oncorhynchus is a genus of fish in the familySalmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greekonkos ("hook") and rynchos ("nose"), in reference to the hooked jaws of males in the mating season (the "kype").

The six Pacific salmons of Oncorhynchus are anadromous (migratory) and semelparous (die after spawning). Migration can be affected by parasites. Infected individuals can become weak and probably have shortened lifespans. Infection with parasites creates an effect known as culling whereby fish that are infected are less likely to complete the migration.[1]Anadromous forms of Oncorhynchus mykiss known as steelhead are iteroparus. The Coastal cutthroat trout form of Oncorhynchus clarki is considered semi-anadromous as it spends short periods of time in marine environments.

Several late Miocene [about 7 million years ago (Mya)] trout-like fossils in Idaho, in the Clarkia Lake beds, appear to be of Oncorhynchus.[2] The presence of these species so far inland established Oncorhynchus was not only present in the Pacific drainages before the beginning of the Pliocene (5–6 Mya), but also that rainbow and cutthroat trout, and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between Oncorhynchus and Salmo (Atlantic salmon) must have occurred well before the Pliocene. Suggested dates ions have gone back as far as the early Miocene (about 20 Mya).[3][4] One fossil species assigned to this genus, O. rastrosus, the sabertooth salmon (synonymSmilodonichthys), is a 9-foot (2.7 m)-long species known from Late Miocene to Pleistocenefossil.[5]

Speciation among Oncorhynchus has been examined for decades, and a family "tree" is not yet completely developed for the Pacific salmonids. Mitochondrial DNA (mtDNA) research has been completed on a variety of Pacific trout and salmonid species, but the results do not necessarily agree with fossil research, or molecular research. Chum, pink and sockeye salmon lineages are generally agreed to have diverged in the sequence after other species.[3] Montgomery (2000) discusses the pattern of the fossil record as compared to tectonic shifts in the plates of the Pacific Northwest of America. The (potential) divergence in Onchorhyncus lineages appear to follow the uprising of the Pacific Rim. The climatic and habitat changes that would follow such a geologic event are discussed, in the context of potential stressors leading to adaptation and speciation.[4]

One interesting case involving speciation with salmon is that of the kokanee (landlocked) sockeye. Kokanee sockeye evolve differently from anadromous sockeye—they reach the level of "biological species". Biological species—as opposed to morphological species—are defined by the capacity to maintain themselves in sympatry as independent genetic entities. This definition can be vexing because it apparently applies only to sympatry, and this limitation makes the definition difficult to apply. Examples in Washington, Canada, and elsewhere have two populations living in the same lake, but spawning in different substrates at different times, and eat different food sources.[6] There is no pressure to compete or interbreed (two responses when resources are short). These types of kokanee salmon show the principal attributes of a biological species: they are reproductively isolated and show strong resources partitioning.

A general decline in overall Pacific salmon populations began in the mid 19th century. As the result of western expansion and development in the U.S., experts estimate salmon populations in the Columbia River basin had been reduced to less than 20% of their pre-1850 levels by 1933.[7] In 2008, Lackey estimated that Pacific salmon stocks in the Pacific Northwest were less that 10% or their pre-1850 numbers.[8] Many of the remaining salmon runs are dominated by hatchery raised salmon, not wild salmon.[8] Many isolated subspecies of the Pacific trouts, particularly those of Oncorhynchus mykissrainbow trout and Oncorhynchus clarkicutthroat trout have declined in their native ranges. Many local populations or distinct population segments of anadromous forms of steelhead have declined in their native ranges. The resulting declines have resulted in a number of populations of Oncorhynchus species or subspecies being listed as either endangered, threatened or as "Species of Special Concern" by state, federal or international authorities. Two Oncorhynchus clarki subspecies are considered extinct.[9] Declines are attributed to a wide variety of causes--over fishing, habitat loss and degradation, artificial propagation, stocking, and hybridization with or competition with introduced, non-native species. For example, the Yellowfin cutthroat trout (Oncorhynchus clarki macdonaldi) is extinct as a result of the introduction of non-native rainbow trout into its native waters.[9]

Declines in the abundance of wild salmon due to over fishing placed greater pressure on hatcheries to increase production and restore the wild salmon stock to supply fisheries.[10][11] The problem is that hatcheries can never truly replicate the environment of wild salmon, an issue which often results in physiological and behavioral differences between wild salmon and those reared in hatcheries. These differences are often the product of genetic changes associated with inbreeding, artificial selection, and natural selection as well as different environmental pressures acting on hatchery fish than wild populations.[12] Due to the size selective nature of fishing favoring larger fish, a reduction in average size of the adult salmon has been observed over time. The smaller salmon make a greater proportion of the remaining individuals continuing the population, and problems arise when these hatchery-reared fish are introduced into the wild populations. Unlike wild salmon, larger salmon are selected for in hatcheries and are typically much larger than wild salmon.[13] The result is that hatchery-produced salmon tend to out-compete wild salmon for space, food, and other resources. Some salmon species in hatcheries exhibit predatory behavior toward wild salmon because they grow to be much larger. Regardless of whether predation is observed, natural social interactions are disturbed by the release of large numbers of hatchery-reared salmon where wild populations are low because salmon in hatcheries naturally have a higher propensity towards aggressive behavior.[14] Overall, natural salmon populations are put at risk when hatchery-reared salmon populations are introduced due to competition for resources, predation by larger individuals, and negative social interactions that upset the natural order observed in wild salmon populations. As a result, wild salmon populations are steadily dropping as the pressure to continue breeding salmon in hatcheries increases. Conservation efforts that work to place limitations on hatcheries to increase the wild salmon populations are hindered by financial pressures because hatcheries effectively support many states economically by accounting for over 70% of the salmon harvested for recreational and commercial purposes.[15]

Pacific salmon are harvested throughout the world as a source of food in countries ranging from the United States to South Korea.[16] Over the past century, pacific salmon have been extensively fished through both recreational, artisan and commercial fishing. In fact, since the 1970s there has been a nearly threefold increase in catch of pacific salmon.[13] As this catch has increased, a selection of reduced body size has been observed. In Japanese Chum Salmon, for example, between 1970 and 1988 there has been a continuous decrease in body weight averaging between 11 and 32 percent.[17] In part, this decline in body weight has been related to the size selective effect of fishing gear used in the harvesting of salmon populations.[10] Salmon of larger body weight are more apt to be caught during fishing efforts, causing lower body weight to be a beneficial character trait for survival. Thus, pacific salmon have become continuously smaller in body size. However, studies have also shown that for pacific salmon a larger mean size at the time of reproduction increases the survival of offspring.[18] The life history of salmon favors delayed reproduction because fecundity increased with body size.[16] Consequently, the smaller body size of salmon results in a negative impact on population growth by decreasing the survivability of progeny, and thus decreasing the growth rate of populations. This reduction of productivity in pacific salmon is, in part, seeded in the overfishing and has caused a reduction in population sizes throughout pacific salmon species. Today, it seems that population numbers of pacific salmon are on the rise, however the consequences from the overfishing in the 70s and 80s are still being reflected with the average body size of salmon being smaller than before the event of overfishing.

There has been evidence that the sockeye salmon are affected by thermal conditions and their responses to temperature are relatively strong and tend to vary from region to region. Canada has also used the Species at Risk Act to recognize the importance of biological diversity when it come to the conservation of the salmon population.[19] This means that multiple species of salmon would be looked at when it comes to conservation as well as multiple areas that each species live in. COSEWIC, a Canadian organization for the conservation of species, has named the Interior Fraser River Coho, the Cultus Lake Sockeye, and the Sakinaw Lake Sockeye to all be endangered. In British Columbia sockeye salmon in four different watersheds were certified by the Marine Stewardship Council or MSC as sustainable fisheries in July 2010 and the certification is good for a period of five years.[20] In 2011 MSC also certified the Pink Salmon Fishery and as of 2012 The Chum Salmon Fisheries started their review under the MSC to become certified as a sustainable fishery.[21]

The US government has been working developing a nation wide policy for the salmon populations.The Pacific Salmon Stronghold Conservation Act was re-submitted to congress and if passed will create geographic strongholds for salmon populations.[22] Other policies include the Wild Salmon Policy which was enacted in 2005 and its number one focus is the conservation of salmon off of the coasts. Even localized policies have begun, with one in Oregon which focuses on the southernmost watershed and was approved January 2013.[23] In the Alaskan efforts, there is evidence of eight known regional groups of survival. It is also seen that the emigration of smolts (young salmon) from freshwater to other areas such as marine areas have shown significant consequences on the survival of different salmon groups. The Alaska Department of Fish and Game first received MSC, Marine Stewardship Council, Certification in sustainable seafood back in 2000.[21] Each certification is good for a period of five years, with yearly check ups to ensure that the fishery remains sustainable. It was renewed again in 2007, but in 2012 The ADFG left the program. The Annette Island Reserve salmon fishery is under the control of the Metlakatla Indian community and as such was not included in the previous assessments of the Alaskan fisheries. It received it’s sustainability certification in June 2011.[21]The Wild Salmon Center is a non profit organization that works on promoting conservation efforts for salmon worldwide and in the United States has secured some of its nine protected locations equaling 8 million acres for protected watershed areas for the west coast salmon.[22] Other efforts of the Wild Salmon Center include combating illegal fishing, maintaining sustainable fisheries, and creating local watersheds as new habitats.[24]

Poaching is a threat to Oncorhynchus salmon and steelhead populations in Russia. It is estimated that illegal catching of salmon is 1.5 times more than the reported catch. The Wild Salmon Center is working with Russian authorities to try and help improve traceability systems so that markets and distinguish between legal sustainable salmon and the illegal salmon.[25] The Wild Salmon Center has secured some of its protected locations for the salmon populations. In efforts with the WWF, the Wild Salmon Center was also able to have a sockeye salmon fishery certified as completely sustainable in 2012.[26] The Iturup Island Pink and Chum Salmon Fishery was first certified in 2009 and was the first Russian salmon fishery to receive certification in sustainability by MSC.[21] Other fisheries that were certified by MSC include the Northeast Sakhalin Island Pink Salmon, certified in June 2012, and the Ozernaya River Sockeye Salmon, certified in September 2012. The Aniva Bay Pink Salmon and the Sakhalin Island Pink salmon are both under review by the MSC.[21]

Some of the species in this genus are highly variable and a number of now-obsolete taxa have been described. In 1989, morphological and genetic studies by Gerald Smith and Ralph Stearley indicated that trouts of the Pacific basin were genetically closer to Pacific salmon (Onchorhynchus species) than to the Salmos–brown trout (Salmo trutta) or Atlantic salmon (Salmo salar) of the Atlantic basin.[30] Thus, in 1989, taxonomic authorities moved the rainbow, cutthroat and other Pacific basin trouts into the genus Oncorhynchus.[9] Currently, 12 species and numerous subspecies in this genus are recognized:[31] Behnke (2002).[9]

^ abBeamish, R.J.1997. "ICES Journal of Marine Science." Hatchery and Wild Production of Pacific Salmon in Relation to Large-scale, Natural Shifts in the Productivity of the Marine Environment. N.p., n.d.

Stearley, R.F. & Smoth, G.R. (1993): Phylogeny of the Pacific trout and salmon (Oncorhynchus) and the genera of family Salmonidae. Transactions of the American Fisheries Society122(1): 1-33. DOI:10.1577/1548-8659(1993)122<0001:POTPTA>2.3.CO;2HTML fulltext

Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. They also reproduce in clear, cold, moderately deep lakes. They are native to the alluvial or freestone streams that are typical tributaries of the rivers of the Pacific basin, Great Basin and Rocky Mountains. Cutthroat trout spawn in the spring and may inadvertently but naturally hybridize with rainbow trout, producing fertile cutbows. Some populations of the coastal cutthroat trout (O. c. clarkii) are semi-anadromous.

Several subspecies of cutthroat trout are currently listed as threatened in their native ranges due to habitat loss and the introduction of non-native species. Two subspecies, O. c. alvordensis and O. c. macdonaldi, are considered extinct. Cutthroat trout are raised in hatcheries to restore populations in their native range, as well as stock non-native lake environments to support angling. The cutthroat trout type species and several subspecies are the official state fish of seven western U.S. states.

The scientific name of the cutthroat trout is Oncorhynchus clarkii. Cutthroat trout were the first New World trout encountered by Europeans when in 1541, Spanish explorer Francisco de Coronado recorded seeing trout in the Pecos River near Santa Fe, New Mexico. These were most likely Rio Grande cutthroat trout (O. c. virginalis)[4] The species was first described in the journals of explorer William Clark from specimens obtained during the Lewis and Clark Expedition from the Missouri River near Great Falls, Montana, and these were most likely the westslope cutthroat trout(O. c. lewisi). As one of Lewis and Clark's many missions was to describe the flora and fauna encountered during their expedition, cutthroat trout were given the name Salmo clarkii in honor of William Clark.[1] In 1836, the type specimen of S. clarkii was described by naturalist John Richardson from a tributary of the lower Columbia River, identified as the "Katpootl",[1] which was perhaps the Lewis River as there was a Multnomah village of similar name at the confluence. This type specimen was most likely the coastal cutthroat trout subspecies O. c. clarkii.[5] Until the 1960s, populations of westslope cutthroat trout and Yellowstone cutthroat trout were lumped into one subspecies; Salmo clarkii lewisii. Biologists later split the group into two subspecies, christening the name Westslope cutthroat trout with the lewisii name which honors explorer Meriwether Lewis and renaming the Yellowstone cutthroat trout Salmo bouvierii,[6] the first name given to the Yellowstone cutthroat trout by David Starr Jordan in 1883 honoring a U.S. Army Captain Bouvier.[7]

Behnke in his salmon and trout handbook of 2002 recognized 14 subspecies of cutthroat trout that are each native to a separate geographic area.[10] Not all of them were scientifically described, and different views on the taxonomic identities have been presented in some cases.[11][12] It has been suggested that the cutthroat trout evolved from a common Oncorhynchus ancestor that migrated along the Pacific coast and into the mountain west primarily via the Columbia and Snake river basins 3-5 million years ago, in the late Pliocene or early Pleistocene epochs. These epochs had repeated glacial and interglacial periods that would have caused repeated fracturing and isolation of cutthroat trout populations, eventually resulting in the different subspecies found today.[13] The 14 subspecies are found in four evolutionary groups—Coastal, Westslope, Yellowstone and Lahontan.[3]

Throughout their native and introduced ranges, cutthroat trout vary widely in size, coloration and habitat selection. Their coloration can range from golden to gray to green on the back. Cutthroat trout can generally be distinguished from rainbow trout by the presence of basibranchial teeth at the base of tongue and a maxillary that extends beyond the posterior edge of the eye.[28] Depending on subspecies, strain and habitat, most have distinctive red, pink, or orange linear marks along the underside of their mandibles in the lower folds of the gill plates. These markings are responsible for the common name "cutthroat", first given to the trout by outdoor writer Charles Hallock in an 1884 article in The American Angler.[29] These markings are not unique to the species, some coastal rainbow trout (Oncorhynchus mykiss irideus) and Columbia River redband trout(O. m. gairdneri) populations also display reddish or pink throat markings.[13]

At maturity, different populations and subspecies of cutthroat trout can range from 6 to 40 inches (15 to 102 cm) in length, depending on habitat and food availability. Sea-run forms of coastal cutthroat trout average 2 to 5 pounds (0.9 to 2.3 kg). The length and weights of mature inland forms vary widely depending on their particular environment and availability of food. Stream-resident fish are much smaller, 0.4 to 3.2 ounces (11 to 91 g), while lacustrine populations have attained weights ranging from 12 to 17 lb (5.4 to 7.7 kg) in ideal conditions.[13] The largest cutthroat trout subspecies is the Lahontan cutthroat trout (O. c. henshawi). These fish average 8 to 9 in (20 to 23 cm) in small streams and 8 to 22 in (20 to 56 cm) in larger rivers and lakes. In ideal environments, the Lahontan cutthroat trout attains typical weights of 0.25 to 8 lb (0.11 to 3.63 kg).[13] The world record cutthroat trout is a Lahontan at 39 in (99 cm) and 41 lb (19 kg).[30]

Cutthroat trout usually inhabit and spawn in small to moderately large, clear, well-oxygenated, shallow rivers with gravel bottoms. They are native to the alluvial or freestone streams typical of tributaries of the Pacific Basin, Great Basin and Rocky Mountains. They spawn in the spring, as early as February in coastal rivers and as late as July in high mountain lakes and streams. Spawning begins when water temperatures reach 43 to 46 °F (6 to 8 °C).[31] Cutthroat trout construct a redd in the stream gravel to lay eggs. The female selects the site for and excavates the redd. Females, depending on size, lay between 200 and 4,400 eggs. Eggs are fertilized with milt (sperm) by an attending male. Eggs hatch into alevins or sac fry in about a month and spend two weeks in the gravel while they absorb their yolk sack before emerging. After emergence, fry begin feeding on zooplankton. Juvenile cutthroat trout typically mature in three to five years.[32] Lake-resident cutthroat trout are usually found in moderately deep, cool lakes with adequate shallows and vegetation for good food production. Lake populations generally require access to gravel-bottomed streams to be self-sustaining, but occasionally spawn on shallow gravel beds with good water circulation.[31]

Cutthroat trout naturally interbreed with the closely related rainbow trout, producing fertile hybrids commonly called "cutbows". This hybrid generally bears similar coloration and overall appearance to the cutthroat trout, usually retaining the characteristic orange-red slash. Cutbow hybrids often pose a taxonomic difficulty when trying to distinguish any given specimen as a rainbow or cutthroat trout.[33] In addition, cutthroat trout may hybridize with O. gilae the Gila trout and O. apache the Apache trout in regions where their ranges overlap.[34]

Cutthroat trout are native to western North America and have evolved through geographic isolation into 14 subspecies, each native to a different major drainage basin. Native cutthroat trout species are found along the Pacific Northwest coast from Alaska through British Columbia into northern California, in the Cascade Range, the Great Basin and throughout the Rocky Mountains including southern Alberta.[36] Some coastal populations of the coastal cutthroat trout (O. c. clarkii) are semianadromous, spending a few months in marine environments to feed as adults and returning to fresh water from fall through early spring to feed on insects and spawn. Cutthroat trout have the second-largest historic native range of North American trout; the lake trout(Salvelinus namaycush) having the largest.[37] Ranges of some subspecies, particularly the westslope cutthroat trout (O. c. lewisi) have been reduced to less than 10 percent of their historic range due to habitat loss and introduction of non-native species.[33]

Although members of Oncorhynchus, the Pacific trout, three subspecies—the westslope (O. c. lewisi), the greenback (O. c. stomias) and Yellowstone cutthroat trout (O. c. bouvierii)—evolved populations east of the Continental Divide in the upper Missouri River basin, upper Arkansas and Platte River basins and upper Yellowstone River basin, each which drain into the Atlantic basin via the Mississippi River. Scientists believe that the climatic and geologic conditions 3 to 5 million years ago allowed cutthroat trout from the Snake River to migrate over the divide into the Yellowstone plateau via Two Ocean Pass. There is also evidence that Yellowstone Lake once drained south into the Snake River drainage.[38] Evidence suggests that the westslope cutthroat trout was able to establish populations east of the divide via Summit Lake at Marias Pass which at one time connected the Flathead River drainage with the upper Missouri River drainage.[39] Scientists speculate that there are several mountain passes associated with the headwaters of the Colorado River drainage and Arkansas/Platte River drainages that would have allowed migration of cutthroat trout east of the divide.[40]

Cutthroat trout have been introduced into non-native waters outside their historic native range, but not to the extent of the rainbow trout (O. mykiss).[35] Within the native range of the Yellowstone cutthroat trout, U.S. Fisheries Bureau and National Park Service authorities introduced Yellowstone cutthroat trout into many fishless lakes in Yellowstone National Park.[41] Cutthroat trout were introduced into Lake Michigan tributaries in the 1890s and sporadically in the early 20th century, but never established wild populations. A population of Yellowstone cutthroat trout purportedly has been established in Lake Huron.[42] Although cutthroat trout are not native to Arizona, they are routinely introduced by the Arizona Game and Fish Department into high mountain lakes in the White Mountains in the northeastern region of that state.[43]

Cutthroat trout require cold, clear, well-oxygenated, shallow rivers with gravel bottoms or cold, moderately deep lakes. Healthy stream-side vegetation that reduces siltation is typical of healthy cutthroat trout habitat and beaver ponds may provide refuge during periods of drought and over winter.[44][45] Most populations stay in fresh water throughout their lives and are known as nonmigratory, stream-resident or riverine populations.[13] The coastal cutthroat trout (O. c. clarkii) is the only cutthroat trout subspecies to coevolve through its entire range with the coastal rainbow trout (O. m. irideus). Portions of the westslope cutthroat trout's (O. c. lewisi) range overlap with the Columbia River redband trout (O. m. gairdneri), but the majority of its native range is in headwater tributary streams above major waterfalls and other barriers to upstream migration.[46] At least three subspecies are confined to isolated basins in the Great Basin and can tolerate saline or alkaline water.[47]

Various subspecies of cutthroat trout are raised in commercial, state and federal hatcheries for introduction into suitable native and non-native riverine and lacustrine environments. In the early 20th century, several hatcheries were established in Yellowstone National Park by the U.S. Bureau of Fisheries. These hatcheries not only produced stocks of the Yellowstone cutthroat trout (O. c. bouvierii) for the park, but also took advantage of the great spawning stock of cutthroat trout to supply eggs to hatcheries around the U.S. Between the years 1901 and 1953 a total of 818 million trout eggs were exported from the park to hatcheries throughout the U.S.[51] The Lahontan National Fish Hatchery operated by the U.S. Fish and Wildlife Service exists to restore populations of the Lahontan cutthroat trout (O. c. henshawi) in Pyramid, Walker, Fallen Leaf, June, Marlette, and Gull Lakes and the Truckee River in California and Nevada.[52] The hatchery produces about 300,000–400,000 Lahontan cutthroat trout fry annually. The Jackson National Fish Hatchery produces around 400,000 Snake River fine-spotted cutthroat trout (O. c. behnkei) annually to support fisheries in Idaho and Wyoming.[53] The Leadville National Fish Hatchery produces 125,000–200,000 Snake River fine-spotted, greenback cutthroat and rainbow trout annually to support fishing in the Fryingpan and Arkansas River drainages and other Colorado waters.[54] The Bozeman Fish Technology Center, formerly a cutthroat trout fish hatchery in Bozeman, Montana, plays a major role in the restoration of the greenback (O. c. stomias) and westslope cutthroat trout (O. c. lewisi) subspecies.[55]

The historic native range of cutthroat trout has been reduced by overfishing, urbanization and habitat loss due to mining, livestock grazing and logging. Population densities have been reduced and in some cases populations have disappeared though competition with non-native brook, brown, lake and rainbow trout, kokanee salmon, lake whitefish and mysis shrimp which were introduced in the late 19th and early 20th centuries.[56] Scientists believe the westslope cutthroat trout will eventually be extirpated from the large lakes in Western Montana due to the trophic cascades resulting from lake trout and mysis shrimp introductions.[57] The most serious current threats to several subspecies are interspecific breeding with introduced rainbow trout creating hybrid cutbows and intraspecific breeding with other introduced cutthroat trout subspecies. In the Greater Yellowstone Ecosystem, the presence of lake trout (Salvelinus namaycush) in Yellowstone Lake in Yellowstone National Park has caused a serious decline in (O. c. bouvierii).[58] Outbreaks of whirling disease in major spawning tributaries within the native ranges have also caused declines. Most subspecies of cutthroat trout are highly susceptible to whirling disease, although the Snake River fine-spotted cutthroat trout (O. c. behnkei) appears to be resistant to the parasite.[59]

The most serious impact on the genetic purity of most cutthroat trout subspecies results from interspecific and intraspecific breeding resulting in hybrids that carry the genes of both parents. In inland populations, the introduction of rainbow trout from hatchery stocks have resulted in cutbow hybrids that continue to diminish the genetic purity of many cutthroat trout subspecies. The introduction of hatchery-raised Yellowstone cutthroat trout into native ranges of other cutthroat trout subspecies, particularly the westslope cutthroat trout, has resulted in intraspecific breeding and diminished genetic purity of the westslope subspecies. As such, populations of genetically pure westslope cutthroat trout are very rare and localized in streams above barriers to upstream migrations by introduced species.[33] Fisheries biologist Robert J. Behnke attributes the extinction of the yellowfin cutthroat trout (O. c. macdonaldi) and Alvord cutthroat trout (O. c. alvordensis) subspecies to the introduction of non-native rainbow trout.[60]

Anglers at West Thumb, 1897, with a harvest of Yellowstone cutthroat trout

The population at the core of the Yellowstone cutthroat trout's native range, in Yellowstone Lake, declined significantly in the 1960s due to overharvest of mature cutthroat trout by anglers, as well as overharvesting of eggs by hatcheries in the early 20th century. Managers implemented catch and release, which required anglers to return their catches to the lake, and they terminated hatchery operations in the park which allowed the cutthroat trout to recover.[61] Then, in 1994, park officials discovered lake trout (Salvelinus namaycush) in Yellowstone Lake. Although lake trout were established in Shoshone, Lewis and Heart lakes in the Snake River drainage from U.S. government stocking operations in 1890, they were never officially introduced into the Yellowstone River drainage and their presence there is probably the result of accidental or illegal introductions.[62][63] By 2000, the cutthroat trout population had declined to less than 10 percent of its early 20th century abundance. However, aggressive lake trout eradication programs have killed over one million lake trout since 1996, and the hope is that this will lead to a restoration of cutthroat numbers.[58][64] Cutthroat trout co-exist with lake trout in Heart Lake, an isolated back-country lake at the head of the Heart River that gets little angling pressure.[65]

This 31.5-inch (80 cm) cutthroat trout set a new Utah state record. As of March 26, 2011, it was the largest cutthroat trout ever caught and released in Utah.[66]

Cutthroat trout are prized as a gamefish, particularly by fly anglers. They are regulated as a gamefish in every state and province they occur in. From the Yellowstone cutthroat trout fishery in Yellowstone National Park,[61][67][68][69] the unique Lahontan cutthroat trout fishery in Pyramid Lake in Nevada, and the small stream fisheries of the westslope cutthroat trout to saltwater angling for sea-run cutthroat trout on the Pacific coast,[70] cutthroat trout are a popular quarry for trout anglers throughout their ranges. The all-tackle world record is 41 lb (19 kg) caught in Pyramid Lake in December 1925.[30] Their propensity to feed on aquatic and terrestrial insects make them an ideal quarry for the fly angler.[71]

From Alaska to Northern California, coastal cutthroat trout in sea-run, resident stream and lacustrine forms are sought by anglers. Puget Sound in Washington is a stronghold of sea-run cutthroat trout fishing with its many tributaries and protected saltwater inlets and beaches. Fly anglers search for sea-run cutthroat trout along beaches, river mouths and estuaries year round. In the lower reaches of larger rivers, anglers in drift boats float the rivers searching for trout along the wooded shorelines.[72] In addition to a cutthroat trout sport fishery managed by the Alaska Department of Fish and Game, the Federal Subsistence Management Program[73] manages coastal cutthroat trout subsistence fisheries in Southeast Alaska.[74]

Fishing Grounds.—In the river at the lake outlet are the fishing grounds, about a mile from the hotel, while at many places between the lake and canyon excellent fishing is had from shore. The best results in the outlet are had from row boats; they can be rented from the steamboat company who have a supply, as well as competent and experienced oarsmen. Not more than two can successfully fish from one boat. When the grounds are reached, have the oarsman occupy the "stern," as from this position he can manipulate the landing net to a better advantage, the anchor is attached to the "bow." During the trout season (July to September), no better fishing can be found. They average about one and one-half pounds each and are of the salmon myhiss [sic] variety—a catch of 100, three or four hours before sundown, is not unfrequent.

In 1902, anticipating the completion of the east entrance road from Cody, Wyoming, Captain Hiram M. Chittenden supervised the construction of the first "Fishing Bridge" across the outlet of Yellowstone Lake.[77] Fishing Bridge was rebuilt in 1919, and reconstructed in 1937, primarily to accommodate vehicle traffic. Between 1916 and 1931, a large development of campgrounds, cabins, stores and service facilities were built just east of the bridge to support anglers. This area is now known as the Fishing Bridge Historic District.[78] The 1937 bridge boasted pedestrian walkways on either side of the roadway to give more room to anglers. Angling in the river, at Fishing Bridge and in the lake, boomed during the 1950s and 1960s and over harvest caused a significant decline in the fishery. Consequently, in 1973, fishing was no longer permitted from Fishing Bridge.[79]

The Pyramid Lake strain of Lahontan cutthroat trout, source of the 41-pound (19 kg) world record and native to Pyramid Lake, Lake Tahoe and the Truckee River, was brought to near-extinction in the two decades between the 1920s-40s from overharvest, introduced species and loss of spawning habitat. In the 1970s, Pyramid Lake was stocked with Lahontan cutthroat trout strains still surviving in some nearby lakes, but they were not the large Pyramid Lake strain. Although the Paiute tribe had been successful in reestablishing a cutthroat trout fishery on the reservation in Pyramid Lake, the cutthroat trout were not the large fish of the late 19th and early 20th century. In the late 1970, biologists discovered a surviving population of a pure Pyramid Lake strain in a small headwaters stream on the Nevada-Utah border that had at some point around 1900 been introduced into the stream. In 1995, the U.S. Fish and Wildlife Service began rearing these fish in the Lahontan National Fish Hatchery[80] in Gardnerville, Nevada. In 2006, the Pyramid Lake strain of Lahontan cutthroat trout were reintroduced into the lake.[81] As Pyramid Lake has a very shallow shoreline, anglers use ladders to stand comfortably in 3 to 4 feet (0.9 to 1.2 m) of water and cast to trout cruising along shoreline breaks. Considered a "world-class" fishery, anglers routinely catch cutthroat trout exceeding 10 lb (4.5 kg).[82]

^Its range is designated as the Humboldt River distinct population segment of O. c. henshawi by U.S. Fish and Wildlife Service and Nevada Division of Wildlife Trotter, Patrick C. (2008). "Humboldt Cutthroat Trout". Cutthroat: Native Trout of the West (2nd ed.). Berkeley, CA: University of California Press. pp. 191–214. ISBN978-0-520-25458-9.

^Crawford, Stephan Scott (2001). Salmonine Introductions to the Laurentian Great Lakes: An Historical Review and Evaluation of Ecological Effects. National Research Council of Canada. p. 74. ISBN0-660-17639-4.

^Jacklin, Bob; LaFontaine, Gary (2004). Fly Fishing the Yellowstone in the Park. Guilford, CT: Globe Pequot Press. p. 110. ISBN1-59228-076-5. The Yellowstone River is known widely for two things: The Spectacular Yellowstone Falls and a few miles of world-class dry-fly fishing for native cutthroat trout.

Known to locals as "bluebacks", Beardslee trout are found nowhere else, and spawn in the Lyre River, near the outlet of the lake. Beardslee are somewhat difficult to distinguish from the Lake Crescent cutthroat trout, which is also endemic to Lake Crescent, as they only take on the Rainbow colors during spawning.[1]

The spawning grounds of the Beardslee (considered the rarest salmonid in the Olympic National Park) are severely threatened by siltation, and the degradation of logjams in the river used as spawning grounds.[2]

Responding to a proposal from Washington Trout, Olympic National Park has announced an emergency change to fishing regulations on Lake Crescent. On May 24 (2002), Park Superintendent David Morris announced that Lake Crescent and all its tributaries will be open for catch and release angling only. The rule change prohibits the use of down riggers, and requires that anglers use only artificial lures with single barbless hooks and no more than two ounces of weight. The emergency rule took effect June 1, the day the lake opened for fishing.

The new rules are designed to protect Lake Crescent’s population of Beardslee rainbow trout, which has declined to a critically low level. Beardslee trout are a unique form of rainbow trout, native to Lake Crescent, and found nowhere else on earth. They spawn in late winter and early spring in only one small area of the Lyre River, near the outlet of the lake. Washington Trout conducted independent spawning surveys on the Lyre this past spring and found alarming evidence of very low numbers of spawning fish, indicating that the population has experienced a severe decline. This evidence was supported by counts made by Park Service crews that officially counted only 35 spawning redds (slightly higher than WT’s count), the lowest number since official redd counts were begun in 1989.[3]

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Lake Crescent cutthroat trout

The Crescenti cutthroat trout or the Lake Crescent cutthroat trout is a North American freshwater fish, a local form (f. loc.) of the coastal cutthroat trout (Oncorhynchus clarkii clarkii) isolated in Lake Crescent in Washington. While previously attributed to a distinct subspeciesOncorhynchus clarkii crescenti, it is not currently recognized at the subspecies rank.[1] However the cutthroat trout of Lake Crescent do remain distinct. They have the highest known gill raker and vertebrae counts of any coastal cutthroat population. The cutthroat are believed to have been isolated in Lake Crescent after a landslide blocked the eastern outflow of the lake.

Before the introduction of non-native trout to the lake, these fish co-existed with the lake's population of coastal rainbow trout known as Beardslee trout. The cutthroat mostly used the lake's inlet stream Barnes Creek for spawning, while the rainbow trout used the Lyre River for spawning. However in the early 1980s a small cutthroat population was found in the Lyre River that spawns further downstream than the native rainbow trout. Today the cutthroat of Barnes Creek have been hybridized with introduced rainbow into cutbows, but Crescenti cutthroat trout persist in the Lyre River as a genetically pure population (Behnke 1992). A Crescenti cutthroat caught in 1961 set the state record for cutthroats at 32 inches (81 cm) and 12 pounds (5.4 kg).[2][1]